From: Jakub Jelinek <jakub@redhat.com>

	mq_notify (q, NULL)

and
	struct sigevent ev = { .sigev_notify = SIGEV_NONE };
	mq_notify (q, &ev)

are not the same thing in POSIX, yet the kernel treats them the same.  Only
the former makes the notification available to other processes immediately,
see

	http://www.opengroup.org/onlinepubs/007904975/functions/mq_notify.html

Without the patch below,

	http://sources.redhat.com/ml/libc-hacker/2004-04/msg00028.html

glibc test fails.

I looked at mq in Solaris and they behave the same in this regard as Linux
with this patch.  Kernel with this patch passes both Intel POSIX testsuite
(with testsuite fixes from Ulrich) and glibc mq testsuite.